Bok Nal - also known as Malbok - is held on separate days in July and August, supposedly the hottest of the year, when Koreans eat the most dog meat.
The 54-year-old's expletive-ridden rant directed at the "dog torturers" follows his equally outspoken campaign against the controversial Yulin Dog Meat Festival, in China, last month.
Ricky Gervais slams the South Korean's dog meat festival, the Boknal Days, in epic Twitter rant
Millions voiced their anger at the Yulin Dog Meat Festival, which traditionally sees thousands of canines and cats tortured before being killed for meat.
Many of the Chinese animals are believed to be pets, taken from the streets, with hundreds reportedly still wearing their collars.
In contrast, the South Korean 'festival' sees dogs nearly exclusively farmed, rather than taken from the streets.
Humane Society International has been working to end the trade, specifically shutting down two dog meat farms and rescuing the animals.
The actor and director begins his Twitter rant saying that material he has read on the matter has nearly reduced him to tears.
Some people did not appreciate Gervais' swearing:
To his critics, The Office creator had this to say:
Despite the "offensive" language, many people looked beyond the swearing and were in full support of Gervais' views:
Gervais' outspoken condemnation even gained the support of another celebrity, with Hilary Swank chiming in to thank him:
Unlike other Asian countries, where dogs are stolen or snatched from the street, in South Korea they are bred on dog meat farms in appalling conditions.
HSI has started a unique project to actively assist dog farmers to close their farms, and move over to humane alternatives such as blueberry farming instead.
Earlier this year, HSI worked with Change for Animals Foundation to save 57 dogs and puppies from a dog meat farm in South Korea.
The dogs ranged from beagles, poodles, and Korean Jindos to large Tosas and spent their entire lives in small, filthy, crowded cages exposed to all weathers on the farm, waiting to be killed for their meat.
After being rescued, there were taken to their new lives in Northern California.
Lola Webber, HSI Asia campaign manager and CFAF director, said: “Some of these dogs were in a terrible state both physically and mentally.
"They’ve been starved of love their whole lives, living in fear and deprivation. As soon as we opened their cage doors and they realised we weren’t going to harm them, they wagged their tails and licked our faces.
"I felt very privileged to give these dogs the first ever cuddle and kiss of their lives.”
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Wendy Higgins, spokesperson for HSI, said: "We plan more such farm shut downs in the future, but ultimately want to see the South Korean government take responsibility for buying out the dog farmers, who for the most part we’re finding are keen to get out of what is often considered a dirty, shameful business.
"As South Korea farms dogs commercially, we have to acknowledge that people’s livelihoods are dependent on this cruel industry, and for change to be sustainable we need to assist them in learning economically-viable, cruelty-free trades instead."